1. Technical Field
Exemplary embodiments of the present invention relate to an image forming apparatus such as a copier, a facsimile machine, a printer, or a multi-function apparatus combining the capabilities of these devices.
2. Background Art
The image forming apparatuses employing electrophotography, including copiers, facsimile machines, printers, or multi-function apparatuses combining the capabilities of these devices, form an image by fusing a toner image onto a recording medium at a prescribed temperature and pressure, thus fixing the image onto the recording medium.
In an image forming apparatus employing electrophotography, conditions for fixing operation such as a set temperature or pressure need to be considered when fusing and fixing the toner image. In particular, to form a quality image, conditions for fixing the toner image vary depending on the type of the recording medium, because image quality is greatly affected by the type, thickness, humidity, smoothness, and coating of the recording medium.
Smoothness is measured as follows: A test plate is placed against the surface of the recording medium, and a length of time in which a prescribed amount of air flows between the surface of the recording medium and the test plate is measured in seconds. “Coating” here means that the recording medium is coated or printed with ink or coating material.
There is a very high correlation between the smoothness of the recording medium and fixing performance, because a fixing ratio of an image changes depending on a ratio of concavities to convexities in the surface of the recording medium, and in particular in the concave portions of the recording medium. Accordingly, when fixation is performed without the smoothness being considered, a quality image is hardly obtained, and failing to consider the smoothness may cause an abnormal image due to defective fixation.
On the other hand, along with recent improvements in the image forming apparatus and diversification of modes of expression, there are now several hundred varieties of recording media. Further, each recording sheet is not the same and is different due to differences of basis weight and thickness, and many brand sheets exist. Accordingly, to create a quality image, the conditions for fixation need to be set precisely for each type and brand of recording media.